Protecting data-processing networks: For industrials sites or secondary buildings integrating a linked computer network, any single issue at one of these systems will create consequences, more or less,to the safety and productivity of the entire system. It is now more and more crucial to reinforce the level of reliability for these systems: this can be achieved by using a proper surge protection strategy for these sensitive networks . . .

Telecommunication and data transmission devices (PBX, modems, data terminals etc..) are becoming increasingly vulnerable to lightning induced voltage surges. These devices are becoming more complex, sensitive and share a common grounding connection with other networks. This situation increases the risk for these sensitive devices to be stressed by destructive surge voltages, induced by lightning or by electrical switching operations.

Data lines need a wide previous study of the systems to be protected. Each transmission protocol has its own working voltage, type of connection, pin-out, etc. All these data should be well known before designing a surge protection strategy that, firstly, does not affect the user and, secondly, is efficient against transient overvoltages.

Protection of radiocommunication equipment. Radiocommunication systems, connected to antennae, are especially exposed to lightning phenomena, the maximum risk being a direct strike on the antenna pole. Equipment, as GSM/UMTS or TETRA base stations, must consider this risk in order to insure a relevant service continuity . . .

These devices are becoming more complex, sensitive and are currently connected to several networks. This situation increases the risk for these sensitive devices to be stressed by destructive surge voltages, induced by lightning or by electrical switching operations.

Moreover, these devices are nowadays installed at every level of every installation (industrial, commercial and residential buildings), making these possible disturbances unacceptable and/or costly.

To make this telecom or data equipment sufficiently reliable, the installation of a dedicated surge protector, against transient overvoltages, is highly recommended.

Surge protectors for telecom and data transmission terminals could be divided in :